Effects of mescaline and psilocin on acquisition,consolidation, and performance of light-dark discrimination in two inbred strains of mice

Mescaline and psilocin were administered to DBA/2J and C57B1/6J mice swimming in a Y water maze toward a light source (L Procedure, corresponding to innate tendency), or toward the dark (D Procedure, corresponding to the acquisition of a new pattern of behavior). In two sets of experiments the hallucinogens were administered to naive mice before and after each training session, respectively.In the pretrial experiments, the innate tendencies of both strains were improved by both mescaline and psilocin administrations. This effect was similar to that observed in previous investigations following nicotine, chlorpromazine, imipramine, and (for the DBA mice) amphetamine administrations. The acquisition of a new pattern of behavior was improved by the hallucinogens in the C57 mice and impaired in the DBA mice. Opposite effects in the two strains (improvement for the C57, and impairment for the DBA strain) were observed when mescaline, or psilocin, was injected immediately (not 2h) after each training session (D Procedure). These effects were similar to those observed following nicotine administrations in previous studies.In a third set of experiments, mescaline was administered to C57 and psilocin to both C57 and DBA mice previously trained in L or D procedure. The administration of both hallucinogens was ineffective in the C57 strain, while performance disruptions, as previously observed with mescaline, were evident following psilocin in the DBA mice previously trained to swim toward the dark.